Illustration of a prototype Arctic Weather Satellite orbiting the Earth. ESA's Arctic Weather Satellite mission is a proposed constellation of small polar-orbiting satellites that will be able to provide very short-range weather forecasting, known as 'nowcasting', for the Arctic. Each satellite will carry a microwave radiometer that would provide an almost constant stream of temperature and humidity data. The data will be used to track storms and extreme weather and to improve weather forecasts around the world.